An array of spirochetal, protozoan, viral and rickettsial pathogens concurrently infect residents of sites in eastern US in which deer are abundant. The abundance of deer and that of the vector arthropods that depend on this host recently have increased. Several of these deer-associated pathogens cause neurologic disease. The objectives of this study are to (1) determine how frequency meningitis and encephalitis are caused by deer-associated pathogens in residents of the northeastern US and how frequently these pathogens occur in combination; (2) Estimate the burden on human health imposed by these deer-associated pathogen and determine whether confection synergizes pathogenesis. We will look at the outcome following meningitis or encephalitis caused by these pathogens, and whether coinfected people experience a greater severity of acute illness or greater neurologic sequelae than if only one such pathogen were present.